.start-screen {
  display: flex;
  flex-direction: column;
  align-items: center;
  padding: 3rem;
  max-width: 1200px;
  margin: 0 auto;
  background-color: #f5f5f5;
  border-radius: 10px;
  box-shadow: 0 0 10px rgba(0, 0, 0, 0.1);
}

.start-screen h1 {
  font-size: 2.5rem;
  color: #333;
  margin-bottom: 2rem;
}

.mode-selection,
.theme-selection {
  width: 100%;
  max-width: 600px;
  margin-bottom: 3rem;
}

.mode-selection h2,
.theme-selection h2 {
  font-size: 1.5rem;
  color: #444;
  margin-bottom: 1rem;
  text-align: center;
}

.mode-buttons {
  display: flex;
  justify-content: space-around;
  gap: 4rem;
  flex-wrap: wrap;
  margin-top: 2rem;
  width: 100%;
  padding: 0 2rem;
}

button {
  padding: 0.8rem 1.5rem;
  font-size: 1rem;
  border: 2px solid #4CAF50;
  border-radius: 5px;
  background-color: white;
  color: #4CAF50;
  cursor: pointer;
  transition: all 0.3s ease;
}

button:hover {
  background-color: #4CAF50;
  color: white;
}

button.selected {
  background-color: #4CAF50;
  color: white;
}

.theme-select {
  width: 100%;
  max-width: 400px;
  padding: 1rem;
  font-size: 1.1rem;
  border: 2px solid #4CAF50;
  border-radius: 5px;
  background-color: white;
  color: #444;
  cursor: pointer;
  margin: 0 auto;
  display: block;
}

.modal-overlay {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background-color: rgba(0, 0, 0, 0.5);
  display: flex;
  justify-content: center;
  align-items: center;
  z-index: 1000;
}

.modal-content {
  background-color: white;
  padding: 2rem;
  border-radius: 10px;
  max-width: 600px;
  width: 90%;
  max-height: 80vh;
  overflow-y: auto;
  position: relative;
  box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
}

.modal-content h2 {
  font-size: 1.5rem;
  color: #444;
  margin-bottom: 1.5rem;
  text-align: center;
}

.modal-content ul {
  padding-left: 1.5rem;
  margin-bottom: 1rem;
}

.modal-content li {
  margin-bottom: 0.8rem;
  color: #666;
  line-height: 1.4;
}

.close-button {
  position: absolute;
  top: 1rem;
  right: 1rem;
  padding: 0.5rem 1rem;
  font-size: 0.9rem;
  background-color: #f44336;
  color: white;
  border: none;
  border-radius: 5px;
  cursor: pointer;
  transition: background-color 0.3s ease;
}

.close-button:hover {
  background-color: #d32f2f;
}

.button-group {
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
  align-items: center;
  margin-top: 2rem;
  width: 100%;
  max-width: 300px;
}

.button-group button {
  width: 100%;
  font-size: 1.2rem;
  padding: 1rem 2rem;
  background-color: #4CAF50;
  color: white;
  border: none;
  border-radius: 5px;
  cursor: pointer;
  transition: background-color 0.3s ease;
}

.button-group button:hover {
  background-color: #45a049;
}